Controllable length conveyor

ABSTRACT

A controllable length conveyor suitable for use in a packaging machine comprises a pair of conveyor belts which are continuously driven in a given direction at a selected speed. The conveyor belts are mounted on a reciprocable frame and are arranged such that the product being conveyed resides between the belts and a run of each belt firmly engages and transports the product. The belt runs engaging the product can be made to extend and retract in correspondence with the product reaching a succeeding stage of packaging such as sealing.

REFERENCE TO RELATED APPLICATION

This application is a division of copending application Ser. No.08/046,012, filed Apr. 12, 1993, entitled "Packaging Machine Having aConveyor of Controllable Length" .[.pending,.]. .Iadd.now U.S. Pat. No.5,385,004, .Iaddend.which in turn is a continuation-in-part of copendingU.S. patent application Ser. No. 07/967,403 filed Oct. 8, 1992 entitled"Belt Conveyor Providing a Controllable Length of Belt Run", abandoned.

FIELD OF THE INVENTION

The invention disclosed herein relates to a conveyor belt system whoselength of belt run can be variably controlled and is illustrated asbeing applied to a packaging machine.

BACKGROUND OF THE INVENTION

Conveyor belts are frequently used to transport items from one locationto another. A conveyor belt when used as a conveying means normally hasa fixed length or run extending between end rollers on which the belttravels and which are located at the beginning and end of travel of thebelt. Thus, the conventional belt conveyor has an operative surface orrun of fixed length.

There are, however, operations requiring the use of a conveyor belt inwhich the length of the operative surface or run is required to change.An example of a conveyor belt extending between the beginning and theend of a conveyorized scaling process and in which the length of theoperative run is required to periodically change during the course ofmoving items along a path is found in the reciprocable sealing barsection of an automatic film wrapping machine, such as that used to packpoultry for retail sale. As the speed of processing increases in such avariable length belt run system, the need to keep firm control of theproduct being packed also becomes increasingly important. In a widelyused type of poultry packaging machine, a sheet of heat sealable film isformed into a tube around the product being packed. The tube is then cutand sealed along a line transverse to its center line at a series oflocations essentially between successive wrapped items. The cutting andsealing of the film is accomplished by a pair of heated sealing barswhich converge onto the film tube and travel with the tube for aselected distance to permit a dwell time sufficient to adequately sealand cut the tube. The heated bars then separate and move backward totheir starting position. Such a machine is disclosed in Japanese patentNo. 63-33230 to Tadoru Suga for "Operation Control Apparatus Of SealMechanism in Packaging Machine And Method Therefor". To allow thesealing bars to first move with and in the direction of the conveyor andthen move back, there is disclosed in related Japanese patentapplication Ser. No. 4-121,444, filed Apr. 15, 1992, a conveyor having amoving gap on its product carrying surface which reciprocates toaccommodate the reciprocating sealing bars.

In order to maintain proper control of the product being wrapped in theprocess of the Saga disclosure and to improve thereupon, it has beenfound beneficial, according to the present invention, to havecontinuously driven vertical side conveyor belts which are used to holdthe film wrapped package through the time it is sealed and cut off.Therefore, the present invention recognizes that the presence ofcontinuously driven side conveyor belts which essentially elongate asthe conveyor gap moves in one direction and contract as the conveyor gapmoves in the other direction in order to follow the action of thevarying moving gap conveyor surfaces would provide a means for enhancingcontrol of the product being packaged.

Therefore, it is an objective of the present invention to provide a beltconveyor, typically comprising a pair of continuously driven beltsbetween which the product travels, at least one run of which is capableof being changed in operative length.

It is an additional objective of the invention to provide a conveyor,typically comprising a pair of belts between which a product travels,having at least one run which while running continuously in a givendirection may be adjusted in length automatically in coordination with arelated process such as a sealing process in the same machine in whichthe conveyor is mounted.

It is a further more specific objective of the invention to provide aconveyor apparatus having a run which is variable in length whileoperating continuously to transport a product such as a film wrappedpoultry product.

These and other objectives will become apparent from the disclosurewhich follows.

SUMMARY OF THE INVENTION

The present invention provides for general packaging machineapplication, but particularly for applications such as poultrypackaging, a conveyor comprising a belt arrangement, typically in theform of a pair of opposed belts between which the product travels, atleast one run of which while being continuously driven is capable ofextending and contracting so as to vary in operative length. The belt ofthe conveyor passes around a series of parallel rollers in a serpentinepath some of which rollers are fixed in position and some of which aremovable in position. The rollers whose positions can be moved aremounted on a frame which moves reciprocally in synchronism with thesealing mechanism and other machine components in a direction parallelto the conveyor travel. Selected ones of the movable rollers arepositioned outside of the fixed rollers while others of the moveablerollers are positioned between the fixed rollers. In the illustratedembodiments, at least one fixed roller is a driver roller and the otherrollers are idler rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the reciprocal conveyor belt apparatusof the invention disassociated from a packaging machine and illustratedas a single belt in a horizontal orientation without supportingstructure for clarity.

FIG. 2 is a perspective view of a portion of a poultry packaging machineincorporating a pair of reciprocal belt conveyors of the invention invertical orientation on opposite sides of a horizontal belt conveyorshown feeding film wrapped poultry products to a horizontal moving gaptype belt conveyor associated with a sealing mechanism, not shown.

FIG. 3 is a partial side elevation view of one of the verticallyoriented belt conveyors of the invention in operating cooperation with ahorizontal belt conveyor having a moving gap and showing in dashed linesthe position of the vertically oriented belt conveyor and of the gap andthe sealing heads at the end of a sealing cycle.

FIG. 4 is a top plan view of a vertically oriented belt conveyor of theinvention disassociated from the packaging machine and depicting thepath of belt travel when all runs of the belt are mutually parallel.

FIG. 5 is a top plan view of a vertically oriented belt conveyoraccording to the invention disassociated from the packaging machine anddepicting the path of belt travel when three runs of belt are paralleland one run of belt is divergent.

FIG. 6 is a top plan view of a vertically oriented belt conveyoraccording to the invention disassociated from the packaging machine anddepicting the path of belt travel when three runs of belt are paralleland one run of belt is divergent but with the divergent run beingdifferent from that shown in FIG. 5.

DESCRIPTION OF THE INVENTION

The general principles of the conveyor aspects of the present inventiondisassociated from a packaging machine are portrayed in the illustrationof FIG. 1 in which belt 12 of the invention conveyor apparatus 10 isseen to continuously travel in the direction indicated by arrow X. Belt12 of a defined length and uniform width and assumed to form part of apackaging machine follows a path which extends around a fixed drivingroller 16, fixed idler rollers 18, 19, a movable end idler roller 20 anda movable center idler roller 22, all mounted substantially mutuallyparallel. When the conveyor 10 is set such that the run or operativesurface S (on which arrow X is drawn) of belt 12 assumes any givenlength L₁ the operative surface S which is assumed to engage thepackaged product, not shown, appears and acts as in any ordinaryconveyor apparatus. The drive motion is imparted to belt 12 by the fixeddriving roller 16 which is connected to a drive system, such as, forexample, a gear motor (not shown) forming part of the packaging machine.The length of belt 12 is sufficient to follow the path described withadequate tension to maintain proper drive and be free of slack.

Movable end idler roller 20 and movable center idler roller 22 are eachrotatably mounted on a movable frame 14 forming part of the packagingmachine, not shown, which reciprocates in a manner such that when theframe 14 moves, both connected idler rollers 20, 22 move equivalently.Frame 14 is composed of frame members 14a, 14b, 14c and 14d and ismounted on a support structure (not shown) so that frame 14 is able toonly move in a direction parallel to the direction of travel of belt 12,as depicted by double ended arrow A. Since the spacing between movableend idler roller 20 and movable center idler roller 22 is constant, thetensioned length of belt 12 is also necessarily constant. The length ofthe operative run or surface S of conveyor 10 may be increased fromoriginal run length L₁, for example, to a run length L₂ by moving frame14 from its position shown in solid lines in FIG. 1 to its positionshown in dashed lines. The run or operative surface S of conveyor 10 mayconversely be shortened by movement of frame 14 in the oppositedirection. During any such reciprocation of the frame 14, it is to beunderstood that belt 12 is driven constantly in the same direction.

With continuing reference to FIG. 1, it should be noted that the majorportion of belt 12 effectively forms four distinct planar segments orruns P-1, P-2, P-3 and P-4 by being wrapped around the series of thepreviously described rollers according to the invention. It is importantfor belt 12 to retain a constant overall length of belt under tensionand remain slack free during a change in the length of the run oroperative surface S of the conveyor 10, e.g., from run length L₁ to runlength L₂. This is accomplished by employing the pair of verticallyspaced fixed idler rollers 18, 19 and locating moveable rollers 20 and22 and fixed roller 16 in the positions indicated in FIG. 1. Particularemphasis is placed on frame 14 acting to assure a constant distancebetween movable rollers 20 and 22. An alternate possibility recognizedby the invention is that of using a substantially large diameter roller(not shown) in place of the idler rollers 18, 19 and in conjunction withthe rollers 16, 20 and 22 located as seen in FIG. 1. Other alternativebelt arrangements are later described in reference to FIGS. 5 and 6.

A poultry packaging machine apparatus is depicted in FIGS. 2 and 3 inwhich a pair of conveyors 30, 30a built according to the invention areused in cooperation with other conveyor apparatus forming pan of asealing mechanism in the same machine.

According to the perspective view of FIG. 2, a pair of essentiallymirror image conveyors 30, 30a are oriented in essentially parallelvertical orientations and are shown gripping and transporting a filmwrapped poultry package P towards the sealing mechanism. Typicalconveyor 30 while vertically oriented is configured and operatessimilarly to horizontal conveyor 10 of FIG. 1, and employs a fixeddriver roller 36, fixed idler rollers 38, 39, 40, 42 and a reciprocableframe 34 on which rollers 40 and 42 are mounted. Horizontally orientedsupply conveyor 50 on which the poultry package P is supported is drivenin the same direction and at the same speed as conveyors 30, 30a and issituated between conveyors 30, 30a at a lower level than the pair ofvertical belts 32, 31a with the plane of the upper portion of conveyor50 extending between vertical belts 32, 32a being essentiallyperpendicular to the plane of the vertical belts 32, 32a. As supplyconveyor 50 transports the film wrapped poultry package in the directionof arrow Y, conveyors 30, 30a, moving in the same direction and at thesame typically fixed speed as supply conveyor 50, contact side portionsof the film wrapped poultry package P and add significantly to the gripand control maintained on package P during continued transport towardsthe sealing mechanism.

At the discharge end of horizontal supply conveyor 50, the poultrypackage P is transferred to a horizontally oriented gapped conveyor 54which facilitates completion of the transverse seals in the process ofcompleting the poultry package P. Gapped conveyor belt 56 is guided byand passes over a series of later described rollers to form anexaggerated "U" pattern when viewed from the side as best seen in FIG.3. A further detailed view of the configuration and function of gappedconveyor 54 is seen in FIG. 3 to be viewed together with FIG. 2. Supplyconveyor 50 discharges the poultry package P at the left of FIG. 3 andtransfers the poultry package P to gapped conveyor At this stage, it isto be understood that the transverse seals at the leading and trailingends of the film wrapped poultry package P have not been completed.Corner rollers a, b, c, d, seen in FIG. 3, are mounted in fixedpositions on the packaging machine frame (not shown). at least one ofsaid rollers a, b, c or d is connected to a packaging machine drivemeans (not shown) to impart drive to gapped conveyor belt 56 in thedirection indicated by arrow B (FIG. 2). Center rollers e, f, g and h(FIG. 3) are mounted on a gapped conveyor frame 58 which reciprocates(arrow E) according to the cycle of the packaging machine as describedin the previously referred to Japanese patent application Serial No.4-121,444. As gapped conveyor frame 58 moves during the transversesealing operation from its solid line indicated position to its dashedline indicated position, gap G in gapped conveyor belt 56 movesaccordingly. This change in position of gap G, at best seen in FIG. 3causes the upper left belt horizontal surface 62 of belt 56 and upperright horizontal belt surface 64 of belt 56 to vary reciprocally inlength with respect to one another. That is, as the upper horizontalbelt surface 62 and the upper right horizontal belt surface 64reciprocate, belt surface 62 lengthens and belt surface 64 shortens asthe frame 58 moves to the right as viewed in FIG. 3 and belt surface 62shortens and belt surface 64 lengthens as the frame 58 moves to the leftas viewed in FIG. 3. Throughout this reciprocation process, the belt 56continues to move in the direction indicated by arrow B and atsubstantially the same speed as that of conveyors 30, 30a and 50.

In the step of sealing and cutting the wrapping film, sealing bars J,J', initially in the position shown in solid lines in FIG. 3, movetoward each other (indicated by arrows C--C) to a sealing position, thentravel together while in the sealing position along the path of conveyorbelt 56 to the position shown in dashed lines, then separate (indicatedby arrows D--D), and lastly move backward to their initial positions.This reciprocating sealing bar travel system allows bars J, J' tomaintain continuous contact with the wrapping film for the maximum timewhile not requiring the conveyor to slow or stop. The objective of thereciprocal movement of gap G is to allow sealing bars J, J' when sealingto travel along the direction of the conveyor belt as described above.

The use of a gap conveyor with reciprocating sealing bars has been knownas previously stated. However, it has not been known to provide apackaging machine with a conveyor of variable length to feed filmwrapped packages to, and to operate in correspondence with, thereciprocating sealing mechanism as next described.

Gapped conveyor frame 58 is appropriately connected to frames 34, 34a ofvertical conveyors 30, 30a by connecting linkage 60, 60a so that as theupper right horizontal belt surface or run 62 of gapped conveyor 54increases or decreases in length, the vertical belts 32a of theconveyors 30, 30a simultaneously change length by an equivalent amount,as shown in dashed lines at 34' in FIG. 3. In this manner, the belts 32,32a comprising conveyors 30, 30a keep continuous contact with andcontrol over the film wrapped poultry package P while it is beingtransported and sealed.

While not illustrated, it is recognized that frames 34, 34a may bemounted to be transversely slidably or otherwise connected to gapconveyor frame 58 in a manner which permits frames 34, 34a to beadjusted transversely and the spacing between conveyor belts 30, 30a tobe adjusted to accommodate to various widths of the film wrapped packageP as illustrated in U.S. Pat. No. 5,137,099, the contents of which areincorporated herein by reference.

As best illustrated in FIG. 3, it will be noted that conveyor belts 30,30a in the retracted position, shown in solid lines, overlap run 62 ofthe gapped conveyor 54 and maintain this overlapping relation in theextended position shown in dashed lines in FIG. 3. Throughout thischange of position, it should be appreciated that conveyor belts 30, 30acontinue to move at their respective fixed speed and in the directionindicated. Thus, very positive control of the film wrapped package P ismaintained throughout the sealing cycle extending between arrows C--Cand D--D.

FIG. 4 illustrates the construction of the conveyor 30 in top plan viewto show the typical roller and belt configuration of the conveyors 30,30a. Belt 32 is driven by roller 36 which is mounted on and driven by apackaging machine drive (not shown) and belt 32 travels in the directionof arrow X'. Belt 32 wraps around idler rollers 38, 39 whose locationsare fixed on the packaging machine frame. Belt 32 also wraps inserpentine fashion to form four parallel planar segments or runs whichextend around movable end idler roller 40 and movable center idlerroller 42. Both idler rollers 40, 42 are mounted on movable frame 34which is movable in either direction as indicated by arrow F (FIG. 4).As frame 34 moves left or right, both idler rollers 40, 42 move inunison therewith and the run length L i increases or decreasesaccordingly while belt 32 continues to move in the direction of X' atits fixed speed. A physical limit is that frame 34 may only move rightuntil movable center idler roller 42 approaches driver 36 to the extentthat driving contact between driver roller 36 and belt 32 is not lost.However, appropriate modifications can be made to maximize the availablemovement of frame 34.

Whereas the preferred embodiment of the variable conveyor belt inventionis directed to a roller and belt configuration in which all runs of thevariable length belt remain mutually parallel, the invention furtherrecognizes, according to a second embodiment, that it is essential tomaintain parallelism only between those runs of belt which vary inlength. Runs of belt which, in contrast, are fixed in length need not beparallel, adding to design flexibility. Examples of two embodimentshaving divergent, or non-parallel, runs of belt are depicted in FIGS. 5and 6.

A comparison is made between FIG. 4 in which all runs of the packagingmachine variable conveyor belt are parallel to each other and FIGS. 5and 6 in which three runs of belt are parallel and one run isnon-parallel. The line of lateral movement of the packaging machine beltlength-modifying frame, illustrated as arrow F in FIG. 4, arrow R inFIG. 5 and arrow S in FIG. 6 are to be considered the foundation towhich parallelism is compared.

FIG. 5 shows runs 70, 72 and 74 of the packaging machine variableconveyor belt 69 parallel to arrow R, and run 76 non-parallel thereto.Run 72 of FIG. 5 is moved laterally by frame 78, while retaining aconstant length. As the packaging machine frame 78 reciprocates, run 74changes in length in inverse relation to the change in length of run 70.Since the runs which change length as the frame 78 moves laterallyincrease or decrease in length in complementary relation, the inventionrecognizes that runs 70 and 74, consistent with the geometry, mustremain parallel. The invention also recognizes that runs 72 and 76 whichdo not change length need not be parallel to each other, although inFIG. 5, only run 76 is divergent.

With continuing reference to FIG. 5, as the packaging machine frame 78moves from right to left that is, from the solid to the dashed lineposition, run 70 decreases length by the amount indicated by arrow R,and run 74 increases length by the length of arrow R. Movement in theopposite direction causes the converse changes to occur. Throughout thereciprocation of frame 78, the conveyor belt 69 continuously rotates inthe direction of arrow X2 and typically at a fixed speed.

In FIG. 6, a different version of this parallel/non-parallelconfiguration is illustrated. As shown, runs 80, 84 and 86 of thepackaging machine variable conveyor belt 79 are parallel to the movementindicated by arrow S. Run 82 is not parallel thereto. Since run 82exists between the ends of the reciprocable packaging machine frame 88,the invention recognizes that run 82 will not change in length andtherefore need not be parallel to the movement indicated by arrow S.

As frame 88 moves, run 80 and run 84 respectively increase and decreaselength reciprocally. The variable conveyor belt 79 at the same time iscontinuously moving and conveying the film wrapped package (not shown inFIG. 6) in the direction of arrow X3.

Though not illustrated, a third packaging machine variable beltconfiguration having a non-parallel run of belt is achieved by combiningthe divergent sides illustrated in FIGS. 5 and 6, i.e. having both run82 and run 86 divergent from the movement direction of the reciprocablepackaging machine frame 88.

The provision of a film wrapped package transport conveyor which whilerunning continuously in the transport direction is able to extend andretract in length and with one or more runs being non-parallel,increases the flexibility of the packaging machine design. The abilityto vary the belt run angle and the pulley position furthermore allowsaccommodation to many special situations encountered in packagingmachine design.

As will be apparent from the description, the variable packaging machineconveyor belt of the invention is capable of being changed in operativerun length in a variety of packaging machine applications. Theprinciples of the invention are applicable to a variety of packagingmachine belt systems without regard to the material of which thevariable conveyor belt is made or how it might be constructed. Thus, theterm "belt" is intended to be used in a broad sense and to apply tosolid flat belts as illustrated, chain-link belts, narrow belts, beltsfitted with pushers and the like so long as at least one side of thebelt is formed to engage and move the product being packaged along adefined path all of which will be understood by those skilled in theart.

Whereas the embodiments described relate to specific configurations anduses, they are not to be construed as limitations of the scope of theinvention which is to be interpreted according to the claims whichfollow.

What is claimed is:
 1. A belt conveyor apparatus for conveying productsalong a horizontal path, comprising:(a) a pair of opposed continuousconveyor belts .Iadd.having fixed upstream ends and positionabledownstream ends, .Iaddend.each .Iadd.of said belts .Iaddend.having adefined length and width and at least one side formed with a productengaging surface disposed in a vertical plane for engaging and movingsaid products along a defined horizontal path corresponding to a run ofthe belt, said belts being positioned such that said products are.Iadd.received by said pair of belts at the fixed upstream ends thereofand .Iaddend.gripped between said pair of belts while being conveyedthereby; (b) belt guiding and frame means portions of which arereciprocable mounting said belts for substantially slack free travel andin a manner to form substantially the entire length of each said beltinto a plurality of non-coplanar runs some of which are parallel andsome of which are permitted to vary in length and position dependent onreciprocation of the reciprocable portions of said belt guiding andframe means; (c) means operatively associated with said belts forsimultaneously driving said belts continuously in the same direction andat a selected speed; (d) means .Iadd.operable independent of actuationby an operator of said conveyor apparatus .Iaddend.for .Iadd.cyclically.Iaddend.reciprocating the reciprocable portions of said belt guidingand frame means to vary the length and position of those runs permittedto vary while maintaining said belts including those runs permitted tovary moving in said direction and at said speed; and (e) a horizontalconveyor belt driven at the same said selected speed and in the samedirection as said pair of opposed belts, mounted on said belt guidingand frame means and located between said pair of vertical belts andoperative to support said products while being conveyed by said verticalbelts.
 2. A belt conveyor apparatus as claimed in claim 1 wherein saidmeans for driving said belts maintains said selected speed fixed duringreciprocating of said belt guiding and frame means reciprocableportions.
 3. A belt conveyor apparatus as claimed in claim 1 whereinleading ends of said pair of vertical belts are continuously maintainedforward of the horizontal conveyor belt leading end by the positioningof said belt guiding and frame means reciprocable portion.
 4. A beltconveyor apparatus as claimed in claim 1 wherein at least one of whichruns remains fixed in both length and position.
 5. A belt conveyorapparatus as claimed in claim 1 including an auxiliary reciprocablemechanism and wherein said means for reciprocating the reciprocableportions of said belt guiding and frame means operates in synchronismwith said auxiliary reciprocable mechanism. .Iadd.
 6. A belt conveyorapparatus for conveying products along a horizontal path, comprising:(a)a first driven horizontal belt conveyor positioned and adapted toreceive, support and convey products in a direction of travel extendingfrom an upstream to a downstream position and at such downstreamposition to transfer said products to belt conveyor apparatus associatedwith further conveving of said products; (b) a pair of opposedvertically disposed continuous conveyor belts having fixed upstream endsand positionable downstream ends, said fixed upstream ends beingdisposed along opposite sides of said first horizontal belt conveyor atsaid first horizonal belt conveyor's downstream position, each saidvertically disposed belt having a defined length and width and at leastone side located between its said upstream and downstream ends formedfor engaging and moving said products along a defined path correspondingto a run of the said vertically disposed belt, said vertically disposedbelts being positioned such that said products upon reaching saiddownstream position of said horizontal belt are directed from said firsthorizontal belt conveyor at its said downstream position into the saidupstream ends of said vertically disposed belts and are gripped betweensaid pair of vertically disposed belts while being further conveyedthereby in said same direction of travel; (c) belt guiding and framemeans portions of which are reciprocable mounting said verticallydisposed belts for substantially slack free travel and in a manner toform substantially the entire length of each said vertically disposedbelt into a plurality of non-coplanar runs some of which extend in adownstream direction from said first horizontal belt conveyor and arepositioned for engaging said products and are permitted to vary inlength and position dependent on reciprocation of the reciprocableportions of said belt guiding and frame means; (d) means operativelyassociated with said vertically disposed belts for simultaneouslydriving said vertically disposed belts continuously in the same saiddirection of travel as that of said first horizontal belt conveyor andat a selected speed; (e) a second horizontal conveyor belt driven at thesame said selected speed and in the same direction as said pair ofopposed vertical belts mounted on said belt guiding and frame means andlocated between said pair of vertical belts and operative to supportsaid products while being conveyed by said vertical belts; and (f) meansoperable independent of actuation by an operator of said conveyorapparatus for cyclically reciprocating said belt guiding and frame meansto vary the length and position of those vertically disposed belt runsextending downstream of said first horizontal belt conveyor which engagethe products and which are permitted to vary while driving saidvertically disposed belts including those runs permitted to vary inlength in said same direction of travel and at a selected speed..Iaddend.